CVE-2026-7886

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A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.\u00a0 The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a02.3 with a vector\u00a0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.\u00a0Thanks Tristan Mandani for reporting.\u00a0if a site truly has private files, the owner should set up a private storage location https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations outside of the webroot so that permissions can be checked on view as well. 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A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.&nbsp; The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of&nbsp;2.3 with a vector&nbsp;CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.&nbsp;<span>Thanks Tristan Mandani for reporting.&nbsp;</span><div><em>if a site truly has private files, the owner should set up a </em><a title=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\" href=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\"><em>private storage location</em></a><em> outside of the webroot so that permissions can be checked on view as well. 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A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.\u00a0 The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a02.3 with a vector\u00a0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.\u00a0Thanks Tristan Mandani for reporting.\u00a0if a site truly has private files, the owner should set up a private storage location https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations outside of the webroot so that permissions can be checked on view as well. That way, even if a authorized user attaches a file, or otherwise links to it, unauthorized users won't be able to view the file.", "supportingMedia": [{"type": "text/html", "value": "Concrete CMS 9.5.0 and below is vulnerable to&nbsp;IDOR in AddMessage/UpdateMessage via attachments[] parameter which can lead to file permission bypass.&nbsp;The `AddMessage` and `UpdateMessage` conversation controllers accept user-supplied file attachment IDs and load files directly via `$em-&gt;find(File::class, $attachmentID)` without checking per-file permissions (`canViewFile()`). A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.&nbsp; The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of&nbsp;2.3 with a vector&nbsp;CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.&nbsp;<span>Thanks Tristan Mandani for reporting.&nbsp;</span><div><em>if a site truly has private files, the owner should set up a </em><a title=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\" href=\"https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations\"><em>private storage location</em></a><em> outside of the webroot so that permissions can be checked on view as well. 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A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system.\u00a0 The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a02.3 with a vector\u00a0CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.\u00a0Thanks Tristan Mandani for reporting.\u00a0if a site truly has private files, the owner should set up a private storage location https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations outside of the webroot so that permissions can be checked on view as well. That way, even if a authorized user attaches a file, or otherwise links to it, unauthorized users won't be able to view the file."}, {"lang": "es", "value": "Concrete CMS 9.5.0 y versiones anteriores es vulnerable a IDOR en AddMessage/UpdateMessage a trav\u00e9s del par\u00e1metro attachments[], lo que puede llevar a una omisi\u00f3n de permisos de archivo. Los controladores de conversaci\u00f3n 'AddMessage' y 'UpdateMessage' aceptan IDs de archivos adjuntos proporcionados por el usuario y cargan archivos directamente a trav\u00e9s de '$em->find(File::class, $attachmentID)' sin verificar los permisos por archivo ('canViewFile()'). Un usuario que puede publicar en cualquier conversaci\u00f3n puede hacer referencia a cualquier archivo en el gestor de archivos del CMS por su ID secuencial, eludiendo eficazmente el sistema de permisos de archivos. El equipo de seguridad de Concrete CMS otorg\u00f3 a esta vulnerabilidad una puntuaci\u00f3n CVSS v.4.0 de 2.3 con un vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Gracias a Tristan Mandani por el informe. Si un sitio realmente tiene archivos privados, el propietario deber\u00eda configurar una ubicaci\u00f3n de almacenamiento privada https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations fuera del directorio ra\u00edz web para que los permisos tambi\u00e9n puedan verificarse al visualizar. 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